1. Field of the Invention
This invention relates to a device for dispersion of light pulses programmable in spectral amplitude.
2. Description of the Prior Art
In general, it is known that there are numerous devices for dispersing brief light pulses. One of them, proposed for the first time by R. L. Fork et al, “Negative dispersion using pairs of prisms”, published in Optics Letters, May 1984, consists of using a train of two identical reversed prisms (the input surface of the first prism is parallel to the output surface of the second prism).
In the example shown in FIG. 1, describing the prior art relating in particular to the device cited above, two prisms P1, P2, having the same vertex angle α, are arranged head to tail, the input surface of said prism P1 is parallel to the output surface of said prism P2, the distance separating them being L; the output surface of said first prism P1 is consequently parallel to the input surface of said prism P2, the distance separating them being d; the projection of the vertex of said prism P2 on the input surface of said prism P1 is separated by H from the vertex of said prism P1.
The modification of the dispersion characteristic associating the delay time with the optical wavelength is performed by modifying the distance L that separates the input and output surfaces of the prisms P1, P2; the modification of the dispersion characteristic can also be performed by modifying the distance H that separates the vertices of the two prisms P1, P2.